Retrieve the latest ES version

[ezimuel]

This PR adds the get_latest_version() function to retrieve the latest Elasticsearch version automatically.

[acsnyder]

LGTM! At least on my Mac

Do you want to have a fallback in case the API response fails?

[xeraa]

I think the beta / RC releases of 9.0.0 will be picked up as the last version, which is probably not what we want?
I just pulled the JSON file and tried it with a slightly modified shell script.

#!/bin/bash

version_sort() {
    awk -F'.' '
    {
        printf("%d %d %d %s\n", $1, $2, $3, $0)
    }' | sort -n -k1,1 -k2,2 -k3,3 | awk '{print $4}'
}

awk -F'"' '/"version": *"/ {print $4}' stack.json | version_sort | tail -n 1

[ezimuel]

@xeraa I think start-local should install only stable release by default. I'm working to add also a parameter to the script to choose a different version. Using this param folks can decide which version, including a beta if it's available on docker.elastic.co.

[xeraa]

Yes, I also think that start-local should only pick stable releases. But if https://artifacts.elastic.co/releases/stack.json adds the beta and RC releases for 9.0.0 (which I assume it will), this PR will pick them up as the latest / highest version.

[ezimuel]

@acsnyder I think the https://artifacts.elastic.co/releases/stack.json should only show stable releases of Elasticsearch, right?

[xeraa]

The file already includes releases like 8.0.0-rc1 etc

[ezimuel]

@xeraa I didn't notice it, thanks! In that case I think we should remove the x.y.z-* versions in the awk expression. I'll propose a change.

[ezimuel]

@xeraa and @acsnyder I removed the beta and candidate releases and added also the GA versions (since 8.0.0 GA is a stable release but it needs to be converted in 8.0.0 removing the GA suffix). Moreover, I added the test for checking that the latest version is not empty and it's a valid major.minor.patch format.